IMAP and POP3 Server Written Primarily with Security in Mind
http://www.dovecot.org/

Dovecot is an IMAP and POP3 server for Linux and UNIX-like systems,
written primarily with security in mind. Although it is written in C,
it uses several coding techniques to avoid most of the common pitfalls.

Dovecot can work with standard mbox and maildir formats and is fully
compatible with UW-IMAP and Courier IMAP servers as well as mail
clients accessing the mailboxes directly.

This is a wrapper package that will just handle common things for all
versioned dovecot packages.